Question Motherboard failing?

[Mxshii]

Hello everyone,


I have an HP EliteDesk 800 G1, and recently it's been acting strange. Most of the time when I try to turn it on, it doesn't power on immediately. I have to leave it plugged into the wall for around 30 minutes to 1 hour before it responds. When it finally starts working, I notice that the Ethernet port light starts blinking — and only then the power button works and the PC boots.


I took it to two different repair shops, and it worked fine there multiple times. They even disassembled and reassembled it, and it kept working. But as soon as I bring it home, the issue returns. It’s like the system needs to "warm up" or stabilize before turning on properly.

I thought it might be the power supply, even though it's new (bought last year). I tested the PC with a different PSU — same issue, so it's not the power supply.
I also cleaned the PC, applied new thermal paste, and still nothing changed.


However, since the day before yesterday, it's gotten worse — it powers on but gets stuck on the BIOS screen and doesn’t boot any further.


When it finally does turn on, sometimes the BIOS screen freezes or becomes very dim — like the brightness is extremely low and unreadable. Other times it boots normally.


I'm suspecting either a motherboard issue or something related to the electrical power in my house. I had someone check the wall voltage and it turned out to be 208V.
Could this voltage be causing the problem? And is there a solution?


Any help is appreciated!

 

[Lutfij]

I have an HP EliteDesk 800 G1
There are a couple of form factors for the EliteDesk 800 G1, which one do you have?

I took it to two different repair shops, and it worked fine there multiple times.
The only difference in the repair shops and your abode would be the source of power(wall outlet) and the internet connectivity.

I tested the PC with a different PSU
Which would be?

You might want to bring in a certified electrician and scope out the wiring in your abode and if you have a potential grounding issue.
I had someone check the wall voltage and it turned out to be 208V.
If your country is meant to operate at 220VC, then yes that might be an issue. Speaking of which, where are you located?

Moved thread from Motherboards section to Prebuilt & Enterprise section.

 

[Misgar]

I had someone check the wall voltage and it turned out to be 208V.

Most modern ATX PSUs work over the full range 100V to 240V, 50/60Hz, as printed on the label. Since 208V is within the specified voltage range, it should be OK, provided you don't have some other problem (dirty mains full of glitches and transients).

In Europe many moons ago, the mains voltage was a nominal 220V and 240V in the UK. According to this web site "European mains voltage is presently specified as being 230 V+10%/−6% (253-217V)" but the "specification will broaden to 230V +/- 10% requiring electrical goods to operate on a supply anywhere between 207 and 253V."
https://www.epanorama.net/blog/2021/11/15/european-mains-power/

By this standard, 208V is just inside the new European regs. Elsewhere in the world, mains voltages can be all over the place. I've measured as low as 55V (heavily loaded hydel) and as high as 330V AC (petrol genny with broken regulator).

I know someone whose house used to receive AC mains over the 253V limit. We asked the electrity company to investigate and they lowered the voltage tap on the 11kV step down transformer in a nearby field. The computer UPS kept switching in a 20V reduction, i.e. 230V out instead of 250V, which is how we knew the supply was too high.

As @Lutfij says, it might be a grounding issue. ATX PSUs are supposed to be connected to a safety earth, otherwise, if a serious fault develops, computer metalwork could become dangerously "live". In the event of a fault, current flows down to ground, blowing a mains fuse or tripping a house circuit breaker.

 

[Mxshii]

ok guys quick update got an electrician and he measured the voltage of the house, it goes up and down like sometimes its 190v/208v/218v and according to what he said there is current leakage sooo?
i took it to like 10 repair shops and worked fine there idk whats the problem? maybe motherboard maybe grounding issue?
(I am from Egypt btw)

 

[Misgar]

sometimes its 190v/208v/218v

All nicely inside the 100V to 240V continuous operating voltage range of most ATX PSUs. Check the label on your PSU to confirm the voltage range.

A good PSU should cope, provided you don't have "dirty" mains full of nasty transients and glitches.

Is your home at the end of a long electricity transmission line, in an industrial estate full of heavy machinery, near multiple air conditioning units, or in a country with unreliable mains?

Perhaps you could benefit from a line conditioner unit, to iron out the fluctuations. I've seen these in hotel bedroooms hooked up to the air conditioning unit on the wall. Huge heavy metal boxes with a variac (variable voltage transformer). A bit of local research may turn up a unit suitable for use with a computer.

Finally there's the double-conversion always-online UPS option, to completely isolate your PC from the mains, but they tend to be expensive.

There's obviously something about the mains supply in your house that's different to the 10 repair shops. When a friend was having mains trouble, we asked the utility company to check and they left a mains tester plugged into the wall. It recorded mains voltages over a 24-hour period and they collected it a few days later.

and according to what he said there is current leakage sooo?

Leakage is quite normal in an ATX PSU and many other switched mode PSUs found in laptop chargers, TVs, etc.

In the circuit below, two Class-Y common-mode RFI filtering capacitors connect the AC mains Line and Neutral inputs down to Earth. These capacitors create leakage currents. Check out most of Aris' PSU tests in Tom's and you'll see blue Y-class capacitors soldered to the mains input plug. There are more capacitors on most ATX PSU circuit boards.
https://resources.altium.com/p/how-use-class-x-and-class-y-safety-capacitors

Leakage currents involved are usually fractions of a milliAmp, or a few milliAmps at most, so unless you have multiple computers all running at the same time, you shouldn't trip a 20mA or 30mA RCD breaker. The RCD might trip on the over-current surge of an ATX PSU switch on, but these current spikes are typically 40 to100A from Line to Neutral, not leakage currents down to earth.

Did the electrician walk round the house unplugging all electronic equipment, before checking for leakage?